Sahil Bloom Profile picture
Jul 24, 2021 27 tweets 6 min read Read on X
Cognitive biases are systemic errors in thinking that negatively impact decision-making quality and outcomes.

THREAD: 20 cognitive biases to learn (so you can think clearly and make better decisions):
Fundamental Attribution Error

Humans tend to:

(1) Attribute the actions of others to their character (and not to their situation or context).

(2) Attribute our actions to situation and context (and not to our character).

We cut ourselves a break but hold others accountable.
Bandwagon Effect

Humans are a social species - this allowed us to thrive.

But it also has a downside…

It creates a strong tendency to speak, act, or believe things simply because a lot of other people do.

Bandwagon effect is similar to "groupthink" and is very dangerous.
Egocentric Bias

The human tendency is to have a higher view of one's self than is objectively warranted.

In group activities, we tend to overestimate (in comparison to objective measure) the degree and value of our own contributions relative to others.
Naïve Realism

Humans think very highly of themselves (see egocentric bias!).

We tend to believe that we see the world with perfect objectivity (cognitive biases be damned!).

We also assume that people who disagree with us must be ignorant, uninformed, or biased.
Baader-Meinhof Phenomenon

Ever notice that something you just learned seems to pop up everywhere around you?

The Baader-Meinhof Phenomenon says that increased awareness of something creates the illusion that it is appearing more often.

Like seeing 11:11 on your iPhone clock...
Pygmalion Effect

High expectations lead to high performance (and vice versa).

Those who have high expectations placed on them are more likely to internalize these expectations and improve their performance accordingly.

Leaders may attempt to use this to their advantage.
Confirmation Bias

Humans have a tendency to see and interpret information in a manner that supports previously held beliefs.

New data positive? This idea is a slam dunk!

New data negative? Must have been an error in the experiment.

Very common and very dangerous.
Backfire Effect

The "backfire effect" is the tendency for humans to use evidence in direct conflict with their thesis to further strengthen their previously held beliefs.

It is a more dangerous version of confirmation bias (also less common and scientifically contested).
Anchoring

The "anchor" is a reference point of information (usually the first piece of information received on a topic).

All subsequent thinking or decisions are silently "anchored" to this point.

Anchoring has been proven by scientists (and used car salesmen) time and again.
Dunning-Kruger Effect

People with a low ability at a task are prone to overestimate their ability at that task.

Humans are notoriously incapable of objective evaluation of their competency levels.

Remember: Everyone is a genius in a bull market.
The Ben Franklin Effect

"He that has once done you a kindness will be more ready to do you another, than he whom you yourself have obliged."

Doing a favor makes you more likely to do another for that person than them doing a favor for you.

We reinforce our self-perceptions.
Loss Aversion

First identified by famed scientists Amos Tversky and Daniel Kahneman, it says the pain of losing something is more powerful than the pleasure of winning it.

As such, humans will typically do more to avoid losses than they will to seek gains.
Endowment Effect

Related to loss aversion, the endowment effect says that once we have something, we don't want to give it up.

Humans will demand more to give up an object than they would be willing to pay to acquire it.
Availability Bias

Humans evaluate situations based on the most readily available data, which tends to be what can be immediately recalled from memory.

This is how the news cycle impacts our thinking. Its persistent negativity cements a belief that the world is a dark place.
Survivorship Bias

History is written by the victors.

But concentrating on "survivors" and systematically ignoring "casualties" of any situation leads to distortions in our conclusions.

We overestimate the odds of success because we only read books about the successes!
The Ikea Effect

People ascribe significantly more value to objects that they have created or assembled, irrespective of the final quality of the object.

We infuse our own self worth into the object, thereby increasing its value in our minds.
Hindsight Bias

Humans tend to believe that events of the past were more predictable than they actually were.

We examine the past with the benefit of hindsight but fail to recognize its impact on our thinking.

Hindsight bias can meaningfully distort our memories.
Plan Continuation Bias

Humans love plans.

Even when the plan appears to be failing (or no longer an appropriate fit for a given situation), we have a tendency to want to continue.

The dangers of a rigid "stick to the plan!" mentality are very real.
The Gambler's Fallacy

Humans are naturally bad with probabilities.

The Gambler's Fallacy says that we have a tendency to believe that past events alter future outcomes (when they clearly have no impact).

Ever thought you were "due for a win" in roulette. You're falling prey.
Curse of Knowledge

Experts (or generally, intelligent people) tend to make the flawed assumption that others have the same background and knowledge on a topic as they do.

They are unable to teach or lead in an effective manner for those still coming up the learning curve.
Cognitive biases have a profound impact on our thinking and decision-making every single day.

The first step to fighting back? Awareness. I hope this post helped with that!

Enjoy this thread? Follow me @SahilBloom for writing on mental models, business, and more.
I will be turning this thread into a longer-form piece for my newsletter, where I will explore these biases in greater depth (including examples and ways to combat them!).

It will be released in the coming days.

Subscribe below so you don’t miss it! sahilbloom.substack.com
And if you are a job seeker looking to leverage your improved awareness and decision-making skills to advance your career, check out my curated job board, where I share unique roles at high-growth companies in finance and tech.

New roles every week! pallet.xyz/list/thebloomb…
This thread is going to become a multi-part newsletter series on cognitive biases, including examples of each and practical ways to combat them.

Part I will be released this week.

Sign up here so you don’t miss it: sahilbloom.substack.com
The Cognitive Biases Handbook (Part 1 of 2) will hit inboxes tomorrow.

I hope it’s a free resource that you can save and come back to whenever you need a refresher!

Sign up here to receive it: sahilbloom.substack.com
The Cognitive Bias Handbook

The newsletter deep-dive (part 1 of 2) is now live in your inbox and ears! Please enjoy, share, and subscribe if you haven’t already. sahilbloom.substack.com/p/the-cognitiv…

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with Sahil Bloom

Sahil Bloom Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @SahilBloom

Dec 10, 2025
The 10 most dangerous Logical Fallacies:

(bookmark this) Image
Ad Hominem: Attack the Person Image
The Straw Man: Distort to Destroy Image
Read 14 tweets
Oct 9, 2025
How to stop overthinking…

The Poison Arrow Principle:

(a visual thread) Image
There’s an old Buddhist story I love:

Imagine someone is struck by a poisoned arrow… Image
While he asks questions, the poison takes over and he dies… Image
Read 8 tweets
Sep 21, 2025
Everyone needs to hear this…

The Surfer Mentality:

(a visual thread) Image
When a surfer gets up on a wave, they enjoy the present moment… Image
With the wisdom and awareness that there are always more waves coming… Image
Read 8 tweets
Sep 12, 2025
This is good.

I’ve been experimenting with AI financial tools. The new AI Advisor release from Origin is neat.

Every day:

1. What happened in markets
2. What it means FOR YOU

Then prompt AI Advisor for recommendations based on trends.

(not an investor, just a user and fan)Image
Image
Image
The power of stuff like this is in democratizing access to sound financial advice.

There’s a huge segment of the population that will be able to connect financial accounts and get personalized/customized financial guidance at a strong CFP level.
I don’t think it eliminates human financial advisors.

More like augments + broadens access to important information.

Very important.
Read 8 tweets
Aug 28, 2025
The 10 most powerful paradoxes of life:

(a visual thread) Image
The Effort Paradox Image
The Growth Paradox Image
Read 13 tweets
Aug 26, 2025
This relationship concept changed my life…

The Hidden Debt Theory:

(a visual thread) Image
When you avoid a hard conversation, you’re taking on a debt… Image
Time does not heal anything when it comes to relationships… Image
Read 5 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

:(